The present invention relates to a structure for installing a viscous vibration-damping wall and a method of installing the same, and more particularly to a structure for installing a viscous vibration-damping wall whose connecting structure is simple and which, while possessing a sufficient withstanding force, can be manufactured at low cost by making improvements on the structure for installing the viscous vibration-damping wall on a main frame structure, as well as a method of installing the same.
Measures for enhancing the damping performance of structures have been adopted since ancient times to enhance the safety of earthquake resistance of building structures and improve the dwelling ability of structures against the wind and other dynamic external forces. As specific solutions therefor, viscous vibration-damping walls have been put to practical use, and the number of the viscous vibration-damping walls actually adopted has been on an increasing trend in recent years.
The viscous vibration-damping wall is constructed such that an upper-end open housing, which is formed by a pair of steel-made side plates mounted on a base plate and a pair of flange plates disposed on both sides of the pair of side plates, is integrated with a lower-floor girder, an intermediate plate integrated with an upper-floor girder is inserted in it, and a viscous material or a viscoelastic material is placed in the gap therebetween with a predetermined thickness.
To build the vibration-damping wall, connection to a main frame structure is required, but under the present circumstances connection metal plates from the main frame structure for connection to the viscous vibration-damping wall include a large number rib plates and make the joints complex, constituting a factor for higher cost.
Referring to FIG. 13, a description will be given of the connection between a conventional viscous vibration-damping wall and the main frame structure. A base plate 52 of a housing 51 making up a vibration-damping wall 50 is bolted to a flange surface of a rising metal plate 54 disposed on a lower-floor girder 53, while an intermediate plate 55 of the vibration-damping wall has a top plate 56 welded to its tip portion and is bolted to a flange surface of a mounting plate 58 disposed on an upper-floor girder 57.
In this state, when the vibration-damping wall 50 bears a horizontal force due to an external force, bending moment due to the borne shearing force occurs in the top plate 56 and the base plate 52 at the upper and lower ends.
The stress applied to the joints acts as the horizontal shearing force with respect to the bolts at the plane of connection, and at the same time a vertical axial force which is distributed widely at the edge portions of the vibration-damping wall 50 occurs in the bolts at the plane of connection due to the bending moment. As a result, large bending stresses occur in the top plate 56 and the base plate 52 having bolt hole portions arranged horizontally, so that it is necessary to adopt countermeasures for the respective plates.
Consequently, as shown in the drawing, a multiplicity of vertical rib plates 59 and 60 are fixed to the base plate 52 and the top plate 56 as well as the rising metal plate 54 and the mounting plate 58 corresponding thereto, and large-scale reinforcement is provided particularly at the edge portions of the vibration-damping wall. This results in an enormously large increase in cost, and constitutes a hindrance to the connection to a member perpendicular to a girder, and to through holes of sleeves of the facility.
Since the damping performance which can be added to a structure is proportional to the quantity of vibration-damping walls that are installed, it is desirable to adopt a large number of vibration-damping walls. However, since the cost required in the installation is also proportional to the quantity used, it is an important problem to reduce the cost of the building construction of the vibration-damping walls and to prevent adverse effects from being exerted on other execution of works.
To overcome this problem, as shown in FIG. 14, a method of building construction has been proposed in which all the upper and lower flange portions are removed. (Refer to JP-A-10-46865).
In this proposal, as shown in the drawing, a bolting steel plate 72 is provided which has the same thickness as an inner wall steel plate 71 of a vibration-damping wall 70 to be fixed to the underside of an upper-floor girder or a reinforced portion thereof, and the inner wall steel plate 71 of the vibration-damping wall is disposed immediately therebelow. A pair of bolting reinforcing plates 73 are disposed on both sides of the inner wall steel plate 71, and the three steel plates are tightened by high-strength bolts 74 so as to be integrated.
In addition, on a lower floor side, a bolting lower steel plate 76 is welded in advance to lower sides of a pair of outer wall steel plates 75 of the vibration-damping wall, and a steel plate 77 of the same thickness as the bolting lower steel plate 76 is provided on a lower-floor girder, and is integrated therewith in the same way as the upper side.
An assertion is made that it is possible to substantially reduce the cost required for the overall building construction of the vibration-damping wall, since the mechanism for transmitting the stress can be rationalized and the fabrication of the vibration-damping wall itself and the fixing portions can be both simplified by virtue of the construction in which flanged connection in each of the upper and lower portions is eliminated, as described above.
However, with the vibration-damping wall according to this proposal, the vibration-damping wall itself is specially provided with the bolting lower steel plate, the inner wall steel plate is provided with an upper reinforced portion, and the friction-type high-strength bolted connection for jointing adopts a structure in which a multiplicity of bolts are arranged on end portion sides of the vibration-damping wall. Such a construction is a natural consequence of the fact that the bolting lower steel plate and the inner wall steel plate need to simultaneously withstand both the shearing force and the tensile force with respect to the bending moment occurring in the vibration-damping wall. A substantial thickness must be inevitably secured for the bolting lower steel plate, so that the cost of the vibration-damping wall itself is not much different from other conventional vibration-damping walls.
In addition, concerning the handling of the vibration-damping wall, since the structure adopted is such that the vibration-damping wall cannot be self-supported, special attention is required for safety and workability under the circumstances of transportation, storage, and on-site setting.
The present invention provides a structure for installing a viscous vibration-damping wall which is simple while possessing a sufficient withstanding force, and which can be manufactured at low cost by making improvements on the structure for connection at the time of installing the viscous vibration-damping wall on a main frame structure, as well as a method of installing the same.
The structure for installing a viscous vibration-damping wall in accordance with a first aspect of the present invention is a structure for installing a viscous vibration-damping wall in which a housing with its upper end open is formed by uprightly setting a pair of steel-made side plates on a base plate and by disposing a pair of flange plates on both sides of the pair of side plates, an intermediate plate is inserted in the housing, and a viscous material or a viscoelastic material is placed in its gap portion, characterized in that the base plate of the viscous vibration-damping wall in its central portion is provided with high-strength bolt hole portions for connection to a flange of a lower-floor girder, and has on both sides of a group of the high-strength bolt hole portions a pair of gusset plates suspended in the same direction as that of the intermediate plate from the base plate down to a position at a short distance therefrom, that the pair of flange plates respectively have a pair of gusset plates suspended therefrom orthogonally with respect to the intermediate plate down to the position at the short distance from the base plate, that the flange of the lower-floor girder is provided with high-strength bolt hole portions opposing the high-strength bolt hole portions of the central portion of the base plate, that gusset plates opposing the gusset plates suspended from the base plate and gusset plates opposing the gusset plates suspended from the flange plate are embedded in the lower-floor girder on both sides of the high-strength bolt hole portions of the flange of the lower-floor girder, that the viscous vibration-damping wall is connected to the lower-floor girder by appropriately connecting opposing ones of the high-strength bolt hole portions and opposing ones of the gusset plates, and that the viscous vibration-damping wall is connected to an upper-floor girder by directly connecting the intermediate plate and a gusset plate fixed to a flange of the upper-floor girder.
The structure for installing a viscous vibration-damping wall in accordance with second, third, and fourth aspects of the present invention is characterized in that, in the first aspect, the base plate of the viscous vibration-damping wall has in its central portion a joining member, and the joining member is provided with high-strength bolt hole portions, that the joining member and the pair of gusset plates suspended from the base plate are formed integrally, and that base plate portions on both sides of the central portion which are respectively provided with the pair of gusset plates suspended therefrom are raised toward the upper-floor girder relative to the central portion provided with the high-strength bolt hole portions, so as to be respectively provided with steps.
The structure for installing a viscous vibration-damping wall in accordance with a fifth aspect of the present invention is characterized in that, in each of the above-described aspects, the connection of the gusset plates is effected only between each of the gusset plates suspended from the base plate and each of the gusset plates embedded in the lower-floor girder and opposed to the gusset plates, thereby making it possible to provide adjustment in correspondence with the relative magnitude of the vertical stress.
The structure for installing a viscous vibration-damping wall in accordance with a sixth aspect of the present invention is characterized in that, in each of the above-described aspects, a rising metal plate is installed on the flange of the lower-floor girder, and is provided with high-strength bolt hole portions, with the result that it is possible to prevent the base material from being damaged by the provision of bolt holes in the flange of the upper-floor girder which is part of the main frame structure.
The structure for installing a viscous vibration-damping wall in accordance with seventh to 10th aspects of the present invention is characterized in that, in each of the above-described aspects, the connection between the respective gusset plates is effected by one-plane friction-type high-strength bolted connection or two-plane friction-type high-strength bolted connection using a pair of splicing plates.
The structure for installing a viscous vibration-damping wall in accordance with 11th, 12th, and 13th aspects of the present invention is characterized in that the direct connection between the intermediate plate and the gusset plate suspended from the upper-floor girder is effected by one-plane friction-type high-strength bolted connection or two-plane friction-type high-strength bolted connection using a pair of splicing plates, and that each of the splicing plates is divided into a central portion and a pair of side portions.
By virtue of the structure for installing a viscous vibration-damping wall in accordance with the present invention, the top plate, the brackets, and the reinforcing rib plates at various portions which have been used in the conventional building construction of the vibration-damping wall are made unnecessary, and the reduction of the thickness of the base plate and the number of bolts is attained. Further, since the vibration-damping wall is self-supported and stabilized, the safety of construction work and workability are improved.
The method of installing a viscous vibration-damping wall in accordance with the first aspect of the present invention is characterized by comprising the steps of: fixing the lower-floor girder to a pair of pillars disposed on both sides thereof, the lower-floor girder being constructed such that the flange is provided with the high-strength bolt hole portions for connection to the base plate, and the pair of gusset plates opposing the pair of gusset plates suspended from the base plate on both sides of the group of the high-strength bolt hole portions as well as the pair of gusset plates opposing the pair of gusset plates respectively suspended from the pair of flange plates are embedded in the lower-floor girder; setting at a predetermined position the upper-floor girder with which the viscous vibration-damping wall is integrated by connecting the intermediate plate of the viscous vibration-damping wall to the gusset plate disposed on a bracket and by connecting the housing to the upper-floor girder by means of a pair of temporary suspending pieces; appropriately connecting opposing ones of the high-strength bolt hole portions and opposing ones of the gusset plates of the viscous vibration-damping wall and the lower-floor girder; and removing the temporary suspending pieces. Therefore, handling can be made simple, shear deformation of the viscous material can be prevented, and the movability of the vibration-damping wall can be prevented.
The structure for installing a viscous vibration-damping wall in accordance with the first aspect of the present invention is basically a structure for installing a viscous vibration-damping wall in which a housing with its upper end open is formed by uprightly setting a pair of steel-made side plates on a base plate and by disposing a pair of flange plates on both sides of the pair of side plates, an intermediate plate is inserted in the housing, and a viscous material or a viscoelastic material is placed in its gap portion, characterized in that the base plate of the viscous vibration-damping wall in its central portion is provided with high-strength bolt hole portions for connection to a flange of a lower-floor girder, and has on both sides of a group of the high-strength bolt hole portions a pair of gusset plates suspended in the same direction as that of the intermediate plate from the base plate down to a position at a short distance therefrom, that the pair of flange plates respectively have a pair of gusset plates suspended therefrom orthogonally with respect to the intermediate plate down to the position at the short distance from the base plate, that the flange of the lower-floor girder is provided with high-strength bolt hole portions opposing the high-strength bolt hole portions of the central portion of the base plate, that gusset plates opposing the gusset plates suspended from the base plate and gusset plates opposing the gusset plates suspended from the flange plate are embedded in the lower-floor girder on both sides of the high-strength bolt hole portions of the flange of the lower-floor girder, that the viscous vibration-damping wall is connected to the lower-floor girder by appropriately connecting opposing ones of the high-strength bolt hole portions and opposing ones of the gusset plates, and that the viscous vibration-damping wall is connected to an upper-floor girder by directly connecting the intermediate plate and a gusset plate fixed to a flange of the upper-floor girder. Therefore, advantages are offered in that the top plate, the brackets, and the reinforcing rib plates at various portions which have been used in the conventional building construction of the vibration-damping wall are made unnecessary, a simple and rational structure can be formed, and the reduction of the thickness of the base plate and the number of bolts is attained, thereby making it possible to reduce the cost. Further, since the viscous vibration-damping walls can be manufactured without substantially changing a line for manufacturing the viscous vibration-damping walls, and the vibration-damping wall can be self-supported, an advantage can be demonstrated in that the safety of construction work and workability can be improved in all aspects including the manufacture, transportation, temporary storage, and installation.
In addition, since the structure for installing a viscous vibration-damping wall in accordance with the following aspects of the present invention is so arranged that the above-described operational advantages can be attained more actively and efficiently, an advantage is offered in that the intended object can be attained sufficiently.
In addition, the method of installing a viscous vibration-damping wall in accordance with the first aspect of the present invention is characterized by comprising the steps of: fixing the lower-floor girder to a pair of pillars disposed on both sides thereof, the lower-floor girder being constructed such that the flange is provided with the high-strength bolt hole portions for connection to the base plate, and the pair of gusset plates opposing the pair of gusset plates suspended from the base plate on both sides of the group of the high-strength bolt hole portions as well as the pair of gusset plates opposing the pair of gusset plates respectively suspended from the pair of flange plates are embedded in the lower-floor girder; setting at a predetermined position the upper-floor girder with which the viscous vibration-damping wall is integrated by connecting the intermediate plate of the viscous vibration-damping wall to the gusset plate disposed on a bracket and by connecting the housing to the upper-floor girder by means of a pair of temporary suspending pieces; appropriately connecting opposing ones of the high-strength bolt hole portions and opposing ones of the gusset plates of the viscous vibration-damping wall and the lower-floor girder; and removing the temporary suspending pieces. Accordingly, advantages are offered in that installation work at the site and handling are made simple, shear deformation of the viscous material is prevented, and the movability of the vibration-damping wall is prevented.
Hereafter, a description will be given of the embodiments of the present invention with reference to the drawings.